Method and apparatus for loosening bark from pulp wood



.G. P BERKEY. METHOD-AND APPARATUS FOR LOOSENING BARK FROM PULP WOOD.

APPLICATION FILED MAR. 271 1920.

Pat ente d Jan. 3,1922.

' INVENTOR a niran srrs area rates.

GEORGE PHELPS IBERKEY, F 'APPLETON, WISCONSIN.

Specification of Letters Patent.

Patented Jan. 3, 1922.

Application filed March 27,1920. Serial No. 369,170.

T 0 all whom it may concern:

Be it known that I, GEORGE P. Banner, a citizen of the United States,and resident of Appleton, Outagamie County, Wisconsin, have invented newand useful Improvements in Methods and Apparatus for Loosening Bark fromPulp Wood, of which the following is a description, reference being hadto the accompanying drawings, which are a part of this specification.

The invention relates to a method and apparatus for loosening bark frompulp wood preparatory to passing the wood through the drum or tumblingbarkers in order to facilitate the removal of the bark.

In the process of drum barking, as used in paper and pulp mills, it isvery difficult to satisfactorily and economically remove the bark from alarge amount of wood used during the year. Fresh cut or green wood isthe only kind that barks easily, and this sort of wood is available tothe average mill only a short time during each year. As the green wooddries out in storage, the sap and resinous matters between the bark andthe wood dry out and cement the bark tightly to the wood, making removalvery difiicult in comparison with fresh green wood, also, in coldweather the bark is frozen to the wood and an even more diflicultbarking problem is encountered.

In an endeavor to overcome these difficulties the wood is floated fromthe storage to the mill whenever possible and the wetting which eachstick of wood receives in this way helps to some degree in subsequentremoval of bark, varying with the length of time the wood remains in thewater. But this method is not complete or thorough and cannot be madepractically so as the wood must remain in ordinary river water of 4:0 toF. for days or weeks to effectively loosen the bark and such a largewater storage for the logs as would be required for this purpose is notpossessed by the average mill. Furthermore, another difliculty isencountered due to the extreme buoyancy of the wood which will floatonly one-third or onehalf submerged and the wood piled on top will notbe submerged at all, consequently a large portion of the'wood is onlypartially subjected to the action of the relatively cold, and thereforeslow acting, water and such a method must be completely abandoned duringthe winter months when the rivers and water-ways adjoining the mills arefrozen. During such months a mill may resort to the hot pond where asmall area of water close to the mill is kept from freezing by the useof steam. But the cost of such a hot pond is large as there is such alarge surface for evaporation or loss of heat and the wood has such ashort time to remain in the necessarily small pond that very little isaccomplished, and in addition the same drawbacks occur as in the riverwater during the summer months, that is, the comparatively lowtemperature of the water in the hot pond and the buoyancy of the woodare factors which prevent the effective loos: ening of the bark.

By the present method the bark covered wood or logs are subjected to theaction of a relatively small heated body of water while the logs aresubmerged therein by a comparatively inexpensive apparatus useablethroughout the year. Preferably this method is carried out'in acontinuous process of conveying the logs under the surface of a heatedbody of water so that the soaking which they receive in the heated waterdur ing the time they are being conveyed through the tank will besufficient to loosen the bark from the wood so that the bark will comeoff easily as the sticks or logs pound against each other in therevolving cylinders known as barking drums.

The following method, together with the apparatus, gives a comparativelylow cost of installation, continuous, positive operation, low cost ofhandling and maintaining, complete submersion of wood, low cost ofheating and as a consequence of these factors a complete and veryeffective treatment of all the wood, as has been demonstrated on acommercial scale by the use of the apparatus hereinafter described incarrying out the method hereinafter described.

The invention further consists in the method and apparatus for looseningbark rom pulp wood as hereinafter set forth and more particularlydefined by claims at the conclusion hereof.

In' the drawing, Fig. 1 is a vertical sectional view of an apparatus forcarryingout the method of embodying the invention.

In'the drawing the numeral 3 refers to a relatively long,narrow tank ofconcrete or wood for containing warm water which is preferably heated bymeans of steam or other heating agent introduced therein in any suitablemanner, as by means of pipes 3. It is preferred to keep the water inthis tank heated to a relatively higher temperature than that of riverwater in summer, though it will be understood that .the temperatures mayvary, depending upon the length of time that the wood is subjected tothe action of the heated water and the condition and character of thewood.

Within the tank I have shown an endless conveyor l and an endlessconveyor 5, the delivery end of conveyor 5 overlapping the receiving endof conveyor 4:.

Conveyor 4: is a standard type of flat conveyor with or without flights6, the conveyor being so inclined to the surface of the water in thetank 3 that asthe wood floats under it it is carried down and submergedand finally as it reaches the end of the conveyor the wood bobs upward,due to its buoyancy, and strikes conveyor 5.

Conveyor 5 is a standard type of flat or apron conveyor with or withoutflights, with either iron or wooden slats, and soplaced that the loweror carrying portion is submerged in the water of the tank.

These two conveyors are continued in the long tank, which may be of woodor concrete, and extend across the entire width of the tank. Water inthe tank may be heated to any desired temperature.

. For green wood or on occasions where a minimum of soaking is desiredor necessary conveyor 4, or the submerging conveyor, 'need notnecessarily be used as conveyor 5 is so constructed and placed withreference to the surface of the water, as will beapparent from thedrawings, that wood may be floated along the front end 7 and carriedalong and submerged, usually to the depth of one layer of wood only. Theextreme buoyancy of the wood causes it to press tightly against thesubmerged portion 'of the conveyor and it is so carried along in thewater of the tank until it eventually bobs to the surface at the end ofconveyor 5 and is ready to be removed from the tank and taken to thebarking apparatus. 1

When it is desired to increase the capacity,

of the apparatus or give a longer soaking time submerging conveyor 4. isused with conveyor 5. This conveyor runs at a greater speed thanconveyor5 and consequently will pilethe wood up several layers deep underconveyor 5, the number oflayers of wood being regulatedby the speed ofconveyor conveyor 5 under such circumstances conveying several layers ofwood to the delivery endof the apparatus. When the twoiconveyors areused a clamor stop 8 is provided between the conveyors'to prevent thewood from floating up to the surface of the water. In a vat 8 wide 'bylong, with the conveyor 5-yrunning at a speed 'of 6 per minute withonelayer of woodtherewillbe a delivery or ten 1 cordsper hour at the endof the conveyoren0ugh capacity for the average mill. Running in thismanner the wood has 15 minutes of soaking while completely submerged inwater. This is sulfr cient to thoroughly loosen the bark on certainkinds of wood but experience hasshown that themost complete treatment ofaverage storage wood takes place with 20 to 30 minutes in water to F.The action of water at this temperature effects a thorough softening ofthe binding agent between the wood and the bark and the combination ofcomplete submersion and the warm water treatment is more effective after80 minutes treatment than many days of soaking in ordinary riverwater'at 40 to 50 F incompletely submerged. The problem has been solvedby thepresent apparatus due to the use of warm water and completesubmersion, which factors .rapidlyisoften the binding agent. a

The practical results of using this method and apparatus,as proven byseveral months experience with all lands of wood, are:

1. 20 to 50%. increase in capacity of barking drums, thereby requiringfewer drums (which are very expensive), less power and maintenance andless labor in operating.

2. No brooming of wood at ends of the log or stick. Usually when a largepart of the wood comes out of the drums unbarked, as it does withoutthis treatment, the wood has to be picked out and thrown back to gothrough the drums again. The extra pounding so received causes the endsof the sticks to splinter with a resulting loss of wood and, what ismore serious, pounding of fine wood and v dirt into the broomed ends ofthe sticks where it cannot be removed later and so goes into the processand causes aserious deterioration of value of the pulp and paper.

3. Prior to this process by far the best results have been obtained byrunning the barking drums wet, that is, passing the carried suspendedwith the bark that the value of the bark as fuel isseriously impairedand its disposition made difficult and expensive. By the present processthe bark is so thoroughly softened before going to the drums that itcanbe run through the drums dry, that is, without the use of water, therebygreatly increasinglits value as fuel.

4. The-method and apparatus may be used throughout the year witharelatively small steam consumption required to heat the water because ofthe small amount of steam necessary tobe used andthe small area orsurface exposed' to radiation losses.

5, The method and apparatus .provides a positive continuous operationwith small amount of labor required and at a less expense for power,maintenance and original cost than prior processes.

What I claim as new and desire to secure by Letters Patent, is:

1. In an apparatus for preparing pulp wood for the barking process, thecombination of a tank containing Warm water, a conveyor for carrying thewood in a submerged condition through said tank, and a. feeding conveyorhaving its delivery end disposed at a distance from the under side ofthe first conveyor and moving at a greater speed to deliver a pluralityof layers of wood to the first conveyor.

2. In an apparatus for preparing pulp wood for the barking process, thecombination of a tank containing warm water, a conveyor for carrying thewood in a submerged condition through the tank, and an inclinedsubmerging conveyor under the upper end of which the Wood is floated andfrom the lower end of which the wood floats up onto the receiving end ofthe first conveyor.

3. In an apparatus for preparing pulp wood for the barking process, thecombination of a tank containing warm water, a conveyor for carrying thewood in a submerged condition through the tank, a submerging conveyor insaid tank having its delivery end overlapping the receiving end of thefirst named conveyor, and a dam between the overlapping ends of theconveyors.

In testimony whereof, I aflix my signature. 35

GEORGE PHELPS BERKEY.

